Attack and decay system using triode-pentode tubes



1953 v w. J. ANDERSON ETAL 2,818,

ATTACK AND DECAY SYSTEM USING TRIODE-PENTUDE TUBES Filed Aug. 50, 1955 ATTORNEY o a M Y k SQ my )QNN um H QKN m N mm QR u Q Q 4 Unittid t tes Patent ATTACK AND DECAY SYSTEM USING TRIODE-PENTODE TUBES Walter J. Anderson and Howard E. Holman, Chicago,

11]., assignors, by mesne assignments, to Chicago Musical Instrument Company, Chicago, 11]., .a corporation of Illinois Application August 30,1955, Serial No. 531,497

7 Claims. (Cl. 84-1.26)

Our invention relates broadly to electronic organs and more particularly to an attack and decay system for such organs.

One of the objects of our invention is to provide an attack and decay circuit which is reliable and stable in operation and which is capable of control from either or both of two manuals.

Another object of our invention is to provide an attack and decay circuit employing triode-pentode cascaded followers having provision for applying a voltage gradually to either the plate of the pentode section-or the suppressor grid of the pentode section or both with release .of the voltage in a reverse gradual fashion.

A further object of our invention is to provide a cascaded triode-pentode follower circuit in which independent sources of audio tones may be mixed, filtered or combined while gradually increasing or decreasing the voltage on selected electrodes of the pentode section of the follower for correspondingly controlling the audio tones at the outputs of the followers.

Other and further objects of our invention reside in the flip-flop control circuit as described more fully in the following specification by reference to the accompanying drawing which diagrammatically illustrates our invention applied to an electronic organ circuit.

In the accompanying drawing, forming a part of this specification, the figure is a diagram illustrative of my invention.

In carrying out our invention, use is made of the counter system shown and described in the coending application of Walter J. Anderson, Serial No. 531,496, filed August 30, l955, in which system, cascaded aperiodic frequency-halving trigger circuit stages comprising triode-pentode vacuum tubes are employed, such that when pulses ofaudio-frequency are supplied a first stage, output pulses at octavely related frequencies may be selectively derived from the respective stages for conversion thereof into audible sounds by an electroacoustic translating device in response to playing the keyboard of an electronic organ. An electronic organ embodying the invention will include a plurality of similar sets of cascaded stages, generally twelve, each set producing octavely related output pulses corresponding to the vibration frequencies of notes of the same letter in the even tempered musical scale. The organ may comprise one or more manuals, a pedal clavier, stops, couplers and the customary mechanisms and devices for the production at said translating device of sounds simulating those typical of various musical instruments.

The herein disclosed invention has for its primary purpose means for obtaining improved musical results by a simplified electrical network having frequency-halving trigger circuits, the operation and stability of which will not be atfected when withdrawing from any of the cascaded stages the outputs thereof, regardless of the number of times the output of any individual stage is required to be used simultaneously at differentplaces in the organ, such, for example, when the same note is 2 played from dilferent manuals and/or said pedal clavier, and whereby the rate of growth and decay of a tone at said translating device can be controlled as desired for different musical results. As indicated in the accompanying drawing, the invention is embodied in an organ having an upper manual and a lower manual.

While any number of trigger circuit stages can be employed, the accompanying drawing shows a first stage 1 and a second stage 2, coupled in cascade and adapted to be driven in response to a pulse of a given audio frequency conducted to the first stage from a master oscil lator (not shown). The said stages are high vacuum tubes of the triode-pentode type and, as illustrated, the first stage is a triode section comprising a cathode 1a, control grid 1b and a plate 10, and a pentode section comprising a cathode 1a, control grid 1b, screen grid 1d, suppressor grid 1e, and a plate 1c. Similarly, stage 2 has a triode section comprising a cathode 2a, control grid 2b and a plate 2c, the pentode consisting of a cathode 2a, control grid 2b, screen grid 2d, suppressor grid 2e and a plate 20 At 3 and 32 are sources of positive energy for ener gizing playing-key operated switches 4 and 4' of the upper manual of the organ and at 18 and 18 are similar playingkey operated switches for the lower manual of the organ. As shown, conductors 3'0 and 31 connect the respective switches 4, 4- and 18, 18 to said sources 3 and 32. Source 3 is provided with parallel resistances 6, 7 and 8 of predetermined relative values, any one of which can selectively connect said source to conductor 30 by means of an adjustable contact member 9. In like manner, source 32 is adapted to energize lower manual key-operated switches 19 and 19 through any one of parallel resistances 26, 27 and 28 that are selectively coactive with an adjustable contactor 29. Connected across switches 4 and 4' and to ground are condensers 5 and 5" respectively, which condensers are adapted to be charged from source 3 when close-circuiting said switches and discharged upon open-circuiting said switches. The plates in the pentode sections of stages 1 and 2 are connected to the respective switches 4 and 5 by resistances 10 and 10 for impressing positive potential on said plates upon close-circuiting when charging condensers 5 and 5'.

The bus 13 includes resistance 11 connecting the bus with plate 10'. The bus is connected to ground adjacent the output end thereof through resistance 12. The amplifier 16 is coupled to the output of bus 13 through condenser 14 and resistance 15 forming a series path around resistance 12 as shown.

The bus 21 connects to suppressor grid 1e through resistance 20 while the output end of the bus 21 connects to ground through resistance 22. A series path through condenser 23 and resistance 24 provides a coupling means for the amplifier 25 to the output of bus 21. Any number of follower tubes may be provided and connected as represented by tube 2, the plate 20' being connected to bus 13 through resistance 11 and the suppressor grid 22 being connected with bus 21 through resistance 20' The B voltage is supplied to the plates 10' and 2c and/ or to the suppressor grids 1e and 22 from manuals represented by switches 4, 4' and switches 18, 18, respectively. The application of the B voltage is gradual upon either the plate or suppressor grid of each tube and the release of the voltage is also gradual thereby providing for gradual attack and decay. The audio frequency tones may thus be controlled as two independent sources of audio tones available for mixing, filtering, etc. as desired.

As the key switch 4 is closed a positive B voltage is gradually applied to condenser 'ithrough resistor 6 from source 3, switch 9 and lead 30 and depending upon the time constants of condenser 5 and resistor 6, this voltage builds up and is applied to resistor 10 to the plate 1c of eifective to deliver electronically the audio frequency signal from the flip-flop circuit associated with the triode and pentode sections of the tube 1 to the signal bus 13 through resistance 11. This signal is in turn amplified through amplifier 16 to effect a tone reproduction. Thus the attack is gradual. As key switch 4 is released, storing condenser 5 acts as a reservoir for the charge or functions as a battery temporarily until the plate la in conjunction with the leak path through resistance It} and resistance 11 and also the resistance 12 drains off the charge from condenser 5, and during this time the plate delivers an audio signal from its internal associated flip-flop circuit through resistance 11 to the signal bu 13. Thus a gradual decay of audio frequency signaling energy is obtained. Similarly all other pentode plates in the cascade give off a gradual attack and decay tone when played.

When the suppressor grids 1c and 2e are employed to efiect gradual attack and decay the second manual embodying switches 18 and 18 are closed. Switch I18 when closed causes the gradual charging of condenser 19 from the positive potential source 32 through the resistance 26, switch 29 and bus 31, and as a result a gradual positive B potential is supplied to the suppressor grid 1e through resistance 17 and it gradually electronically conducts the flip-flop signal through resistance 20 to the B signal bus 21 serving as a collector leading to amplifier 25 which in turn amplifies the signal and as in the case of the plate of the pentode, as the key switch 18 is released, condenser 19 continues to hold a charge for a duration of time which is dependent upon the conduction of the suppressor grid 1e and upon the lead paths through resistances 17, 2t) and 22. Thus the pentode section of the tube continues to deliver an audio signal to the B signal bus 21 for a given time after the key switch I18 has been released in its up position. Thus gradual attack and decay is secured.

In addition to the controllability of the two separate elements in one controlling tube our invention is directed to the gradual attack and decay in any form of counter such as a multi-vi'orator or EcclesJordan circuit without the use of an extra tube. The decay and attack functions are achieved without disturbing the operation of the counting circuit itself. Heretofore counting circuits have become unstable when an attempt is made to load them or apply voltages other than those values under which such circuits normally operate. In the system of our invention reliable and stable operation is secured independently of the charges applied to the electrodes in effecting gradual attack and decay.

Synchronizing voltage from a master pulse generator (not shown) is applied to the first stage 1 from the input terminal 31) and ground connection 4%. Said master pulse generator may consist of any suitable weldcnown. source, such as a Hartley oscillator. The signal is applied to the junction point 50 between resistors 260 and 270 through the condenser 80 and transmitted to the control grids lb and 1b through condensers 9t) and Till). The plate 16 of the triode section of stage 1 and the screen grid 1d of the pentode section of said stage, in turn, flop and the counter action follows. The plate 10' of the triode section of stage 1 and suppressor grid 12 of the pentode section of stage 1 are electronically coupled to the cathode In, control grid 1b and screen grid 1d of the pentode section. It follows that a flip-flop signal appearing within the elements of the pentode section is also present at the plate 1c and suppressor 1e when keyed to a source of positive potential via resistances 10 and 17 and 4 and 18 respectively. In a similar manner, a synchronizing signal is transmitted from the plate lie of the triode section of said first stage via condenser 180 to the junction point 19 of resistances 60 and 70' of stage 2.

The circuit for stage 1 is completed by resistor 200 which is shunted between control grid 1b of the triode section and the screen grid 1d of the pentode section. The bias on the suppressor grid 1e and control grids 1b and 1b is controlled by cathode resistance 222 and associated shunting condenser 23. The input circuit to the control grid 1b and cathode 1a of the triode section of stage 1 is completed through resistance 240. The positive potential supplied the plate 1c of the triode and the potential supplied the screen grid of the pentode is controlled by resistance 250. The input circuit to the pentode section of stage 1 is completed through resistance 280. The output circuit of stage 1 is completed by resistance 290 which connects between control grid 1b of the pentode section and the plate 10 of the triode section.

The circuit of stage 2 is similar in all respects to the circuit of stage 1 and in order to emphasize the corresponding circuit elements, corresponding elements are indicated by like reference numerals with the prime designation added, i. e. 220', 240', 260, 270, 250, 290', 280', 230', 221. Each follower stage operates in a like manner and the take-off signal is derived from each stage without loading the tube elements or disturbing their operation for counting purposes. The pentode plates 1c and 2c and the suppressor grids 12 and 2e are activated only when positive voltage is applied thereto, thereby maintaining stability of operation of the stage and enabling signal voltage to be derived from either one or both of the stages, regardless of the number of times the same signal voltage is desired to be used. In the instant case, signal voltage can be supplied at the same time to both the upper manual and the lower manual which, in this disclosure of our invention, are designated by switches 4 and 4' (upper manual) and switches 18 and 18' (lower manual) of the organ.

What we claim and desire to secure by Letters Patent of the United States is as follows:

1. The combination comprising an output system; a series of similar flip-flop circuits coupled in cascade and producing output oscillations at octave separation, each of said circuits comprising a vacuum tube having a triode section and a pentode section; a source of positive potential; keying circuits for each of said cascaded flipilop circuits for selectively connecting the plate and the suppressor grid of the pentode section thereof to said source of potential and to said output system for impressing positive potential on said plate and said suppressor grid, thereby withdrawing oscillations from said circuit and delivering same to said output system; and means for and actuable by each of said keying circuits for controlling as a function of time the rate of starting and stopping delivery of oscillations to said output system.

2. The combination comprising an output system; flipflop circuits coupled in cascade and adapted to produce output oscillations at octave separation, each of said circuits comprising a vacuum tube having first and second sections of electrodes in which certain electrodes of the first section are connected to certain electrodes of the second section thereof, said second section having at least one additional electrode external of said circuit from which oscillations produced by the circuit can be withdrawn when positive potential is applied to said electrode; and means including a source of positive potential and switch means for impressing positive potential on the additional electrode for Withdrawing oscillations from said circuit and delivering same to said output system and for controlling as a function of time the rate of starting withdrawal of said oscillations from the circuit and the rate of stopping delivery thereof to said output system.

3. The combination comprising an output system; a series of aperiodic trigger-circuit stages coupled in cascade and producing output oscillations at harmonically related frequencies, each separate stage of said series of stages comprising a vacuum tube having a triode section and a pentode section in which sections, certain electrodes of the triode section are connected to certain electrodes of the pentode section to form an aperiodic trigger circuit and wherein other electrodes of the pentode section are external of said circuit and serve as the only effective points for withdrawing oscillations from said circuit; a source of positive potential; key-operated switches connecting said source of potential to respective ones of said other electrodes for impressing positive potential thereon for withdrawal of oscillations from said circuit; and means connected to said source of potential, the external electrodes and said output system for controlling as a function of time the rate of withdrawal of oscillations from said circuit in response to actuation of said switches and for similarly controlling as a function of time the rate of stopping delivery of oscillations to said output system.

4. The combination comprising an output system; a series of trigger-circuit stages coupled in cascade, each stage comprising a vacuum tube having a triode section and a pentode section in which all electrodes of both said sections except the suppressor grid and the plate of the pentode section are interconnected to form a trigger circuit producing audio signal voltage of a given frequency and wherein said suppressor grid and said plate form points external of said circuit from which signal voltage produced by said circuit can be withdrawn and delivered to said output system; a source of positive po tential; a switch connecting said source to said suppressor grid for impressing positive potential thereon to thereby efiect withdrawal of signal voltage from said circuit when said switch is close-circuited; a second source of potential; a switch connecting said second source of potential to the plate of said pentode section for impressing positive potential thereon to thereby efiect withdrawal of signal voltage from said circuit when said last named switch is close-circuited; and means connected to said swiches and to said suppressor grid and said plate and the output system and actuable by one or both of said switches for controlling as a function of time the rate at which signal voltage is delivered to said output system and for similarly controlling as a function of time the rate of stopping delivery of signal voltage to said output system.

5. The combination of elements for use in the production of tone frequencies adapted to be translated into audible sounds for musical expression, comprising an output system having an audio amplifier; a source producing an audio signal of given frequency; said source comprising a vacuum tube having a set of tube elements consisting of a plate, a control grid and a cathode and a set of tube elements comprising a plate, a control grid, a screen grid and a cathode, in which said sets of tube elements all of said elements except the plate in the second named set are interconnected so as to form a trigger circuit adapted to produce the aforementioned audio signal upon impressing a driving pulse of given frequency on the control grid of the first named set of tube elements; a conductor connected to said output system; a resistance connecting the conductor to said plate of the second named set of tube elements; and condenser-resistive means including a key-operated switch connecting said conductor to said output system for controlling as a function of time the rate of delivery to the output system of the signal produced by said circuit and similarly controlling the rate of stopping delivery of said signal to said output system.

6. The combination as defined in claim 5 wherein said second named set of tube elements includes a suppressor grid located externally of said trigger circuit and wherein condenser-resistive means embodying a key-operated switch and a source of positive potential are employed for delivery of the output signal of said trigger circuit to said output system and controlling as a function of time the rate of delivery of said output signal to said output system and for similarly controlling the rate of stopping delivery of said signal to said output system.

7. The combination of elements comprising a source adapted to produce an output audio signal of given frequency, said source comprising a vacuum tube having a control grid, a cathode and a screen grid comprising elements necessary for the production of said signals and in addition to said elements, a plate and a suppressor grid, each of which is external of said control grid, said screen grid and said cathode; an output system, means including a source of energy for selectively impressing positive potential of any desired magnitude upon either the plate or the suppressor grid or both thereof and delivery of the output signal of said tube to said output system and for controlling as a function of time the rate at which said signal is delivered to said output system and the rate of stopping delivery of said signal to said system.

References Cited in the file of this patent UNITED STATES PATENTS 2,176,525 Firestone Oct. 17, 1939 2,294,178 Hanert Aug. 25, 1942 2,539,826 George Jan. 30, 1951 2,788,693 Seybold Apr. 16, 1957 

